dGrid is not showing all the records of a query

In my application, I'm populating a dGrid with the results of a QueryTask. It's a small dataset of 57 points, but the dGrid is showing the first 25 records (1-25), then the last 7 records (50-57). When I reverse the sorting of the grid by the ObjectID, it's showing records 57-33 and 8-1.

I've created a JSBin to show what's happening. This is how I'm executing the query, populating the grid, and adding it to the content pane.